Ernst Zinner, Lithic Astronomer

UCLA UCLA Previously Published Works Title Ernst Zinner, lithic astronomer Permalink https://escholarship.org/uc/item/0gq43750 Journal Meteoritics & Planetary Science, 42(7/8) ISSN 1086-9379 Author Mckeegan, Kevin D. Publication Date 2007-07-01 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Meteoritics & Planetary Science 42, Nr 7/8, 1045–1054 (2007) Abstract available online at http://meteoritics.org Ernst Zinner, lithic astronomer Kevin D. MCKEEGAN Department of Earth and Space Sciences, University of California, Los Angeles, Los Angeles, California 90095–1567, USA E-mail: [email protected] It is a rare privilege to be one of the founders of an entirely new field of science, and it is especially remarkable when that new field belongs to the oldest branch of “natural philosophy.” The nature of the stars has perplexed and fascinated humanity for millennia. While the sources of their luminosity and their structures and evolution were revealed over the last century, it is thanks to the pioneering efforts of a rare and remarkable man, Ernst Zinner, as well as his colleagues and students (mostly at the University of Chicago and at Washington University in Saint Louis), that in the last two decades it has become possible to literally hold a piece of a star in one’s hand. Armed with sophisticated microscopes and mass spectrometers of various sorts, these “lithic astronomers” are able to reveal stellar processes in exquisite detail by examining the chemical, mineralogical, and especially the nuclear properties of these microscopic grains of stardust. With this special issue of Meteoritics & Planetary Science, we honor Ernst Zinner (Fig. 1) and his stellar career achievements on the occasion of his completion of 70 orbits. We cannot here do proper justice to also honoring his admirable personal qualities that have inspired a generation of scientists to follow his lead in studying the death of stars and the birth of our own star. Fortunately, many of us had an opportunity to celebrate Ernst the scientist—and Ernst the Fig. 1. Ernst K. Zinner, research professor of physics and earth and man—at the SIMS in the Space Sciences: The Zinner Impact planetary sciences at Washington University in Saint Louis (2006). Symposium held at Washington University February 3–4, 2007. This wonderful event, organized by Christine Floss their role in shaping the boy. A deep appreciation of the along with Sachiko Amari, Randy Korotev, Frank beauty of the natural world coupled with a lifelong love of Stadermann, and Brigitte Wopenka, was attended by about classical music, as well as the occasional frustration at the 120 scientists, some of whom have also contributed papers to impermanence of things in the U.S. (particularly the eating this volume. This article presents a partial scientific establishments in the Houston area), would be a few of the biography and a personal view of the “Zinner impact” by one characteristics that would find expression in the man. It was who was fortunate enough to be involved in a small way in natural that Ernst should study physics, which he did at the some of the early adventures. Technische Hochschule in Vienna, obtaining his Diplom- Ernst Zinner was born January 30, 1937, and grew up in Ingenieur in 1960. Following a year of instructing veterinary a beautiful stone house that was built in 1615 (and still stands) students in physics, Ernst took a programming job in in Saint Peter in der Au, a small town in the Austrian Switzerland, primarily to avoid mandatory service in the countryside about 100 miles west of Vienna. He is the oldest Austrian army. However, he soon decided to resume his of five siblings and his father Kunibert was quite a famous graduate studies and applied to various American sculptor. The history of this setting, their house filled with universities, apparently unaware of that country’s interest in a music, and the mountain hillsides filled with butterflies place called Vietnam. He was accepted at Washington (which required catching and cataloguing) would all play University in Saint Louis in 1965 and, ironically, along with 1045 © The Meteoritical Society, 2007. Printed in USA. 1046 K. D. McKeegan his green card, he received another welcome package from potential with instrumental improvements and appropriate Uncle Sam in the form of a draft card. Somehow, Ernst development effort. He also must have had a good hunch that managed to escape that ominous path and succeeded in Ernst Zinner possessed the proper blend of skepticism and obtaining a Ph.D. in experimental particle physics elucidating enthusiasm, as well as the talent, energy, and drive to take on aspects of the K+ → π° µ+ ν decay. Like the K+-meson, the this challenge. Thus began an itinerant existence for Ernst as experimental particle physics group at Washington University he spent much of the remainder of the decade and the had a short lifetime, and it rapidly disintegrated at the same beginning of the next testing instrumentation and exploring time that Ernst filed his dissertation in 1972. A the strengths and limitations of SIMS in several laboratories now-legendary 2:00 A.M. encounter in the elevator of in the U.S. and Europe. The early development of Ernst’s ion Compton Hall Laboratory with Bob Walker, the relatively microprobe skills was accomplished over dozens of trips to recently ensconced McDonnell Professor of Physics, changed Houston where he had a visiting scientist appointment at the the career direction of the then-35-year-old new Ph.D. and led Lunar Science Institute to work on the ARL ion probe at to a three-decades-long collaboration and friendship. The Johnson Space Center. The instrument was housed in a small charismatic Walker charmed Ernst with his enthusiasm for the lab under a stairwell in Building 31. In addition to trying to vast and uncharted scientific opportunities that were available understand the physics of ion yields and primary beam knock- through the analysis of extraterrestrial matter. Zinner bought on effects in depth profiling, Ernst discovered that a into the vision and gave up high-energy physics to become a correction to count rates had to be made whenever someone postdoc on the fourth floor of Compton, in the new walked on the stairs above! While these development efforts Laboratory for Space Physics. were ongoing, Zinner and colleagues continued producing At that time, research of Walker’s “Fourth Floor Group” scientific results related to the interplanetary dust flux, the mostly focused on understanding and exploiting radiation solar wind, and the lunar surface environment (e.g., Crozaz damage in crystalline solids as a proxy record of thermal et al. 1977; Zinner 1980b; Zinner et al. 1977). histories, exposure ages, and radiation environments. Thus, The early struggles with unknown physics and unreliable the first project that Ernst worked on, with Walker as well as instrumentation serve to illustrate several of Ernst’s Janet Borg and Michel Maurette, involved measurements of characteristic qualities. The first are dogged determination the abundance of heavy (Fe-group) ions in the solar wind as and perseverance. As usual, this attitude is underpinned by an recorded by nuclear tracks in mica in an experiment deployed innate optimism, although in this case, frequently tempered by the Apollo 17 astronauts (Zinner et al. 1974). Two thrusts by frustration that scientific progress is slowed by “a stupid followed naturally from Zinner’s first exposure to space machine.” No matter how aggravating, all problems from the science: recognition of a need for better analytical methods subtle (e.g., matrix effects, element-dependent dead time, for micro-analysis and germination of an interest in the mass fractionation laws) to the absurd (see above!) had to be interplanetary dust particles that caused micro-impact craters overcome to assure reliable data. Another characteristic of on the surfaces of lunar soil crystals. The latter was pursued in Ernst’s career is that technical development and scientific collaboration with Donald Morrison of Johnson Space Center applications proceed in a synergistic fashion; thus, ion in a series of papers (Morrison and Zinner 1977; Poupeau implantation is developed as a means for quantifying matrix et al. 1975; Zinner and Morrison 1976). To address the former effects in depth profiling so that analyses of lunar grains could objective, Walker and Zinner set about developing a novel be accomplished. However, it is important to emphasize that surface analysis technique for quantifying elemental Ernst’s ideas regarding technical development have often distributions in complex materials like lunar grains. They taken the long view, recognizing that sustained effort is implanted “marker ions” into the grain surfaces so that necessary to assure that the tools are made ready, so that when isotope analyses could be used to quantify elemental nature cooperates, significant discoveries can be realized. abundances—an innovation on the classic isotope dilution Zinner and Walker had hoped that nature would indeed method (Zinner and Walker 1975). To perform the analyses, cooperate by hiding her treasures in small places, and that they turned to secondary ion mass spectrometry (SIMS) these secrets could be revealed by SIMS. This was not a because of its inherently high depth resolution. radical viewpoint, and in fact others were also developing the Important to realize is that in the early to mid-1970s ion probe for cosmochemical research—especially Ian SIMS was a new technology and the first generation of Hutcheon, first at Chicago and then with Jerry Wasserburg’s commercial ion probes were already earning a well-deserved group at Caltech, and also Bill Compston and colleagues reputation for generating unreliable or uninterpretable results creating the SHRIMP at the Australian National University. (i.e., nonsense).

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